Iran's Fars news agency said the sides had also agreed to hold a second round of talks in the Iraqi capital Baghdad if they made progress in Turkey. There was no immediate comment from the world powers - the United States, Britain, France, Russia, China and Germany.

Iran and officials from the P5+1 group of countries had earlier released conflicting statements about the venue for the talks, scheduled on April 13, raising doubts among some diplomats and analysts over whether the negotiations would happen at all.